Buddhism is like a game manual for this life and the lives after. Some people like to play computer games without reading the game manuals. The result can be full of surprises, exciting and painful. They may end up playing only a small part of the game. According to Buddhism, we have been playing real life for a super long time (eons and eons, billions of years). As a game manual, Buddhism shows how we can guide our present life and future lives, and explore different worlds. This book explains some fundamental ideas in Buddhism. It shows the real life characters that we can play, e.g., humans and bodhisattvas, and the different worlds that we can play in, e.g., the world on Earth and the World of Ultimate Bliss. It also explains the meaning of enlightenment, with an analogy to computer game playing. When a game character is "enlightened", it realizes that it is a human. When a human is enlightened, he/she realizes his/her Buddha nature.